An allergy is an abnormal immune system response to a substance that is typically harmless to most people. This substance, called an allergen, can trigger the body's immune system to produce antibodies, leading .

Cold" and "flu" are both terms used to describe respiratory illnesses caused by viruses, but they are caused by different viruses and have some differing symptoms and severity.

Hypertension, commonly known as high blood pressure, is a medical condition characterized by elevated pressure in the arteries.